Bobbin signal



Aug. 21, 1956 s. TUNSTALL 2,760,024

BOBBIN SIGNAL Filed June 30, 1953 INVENTOR. Spencer Tunstall ATTORNEY.

United States Patent BOBBIN SEGNAL Spencer Tunstall, Flushing, N. Y.

Application June 30, 1953, Serial No. 365,119

7 Claims. (Cl. 200-6115) This invention relates to bobbin signals forindicating when the bobbin in a sewing machine is approachingexhaustion.

A variety of devices for indicating when the thread on a bobbin isnearly exhausted have been proposed, utilizing feelers of various typesacting against the thread on the bobbin. Such devices have, however, notbeen generally adaptable to sewing machines of standard types and haveinvolved difliculties due to interference with the feeding of thethread.

It is an object of the present invention to provide a bobbin signal of asimple character which is readily adapted to use in standard sewingequipment.

Another object of the invention is to provide a bobbin signal involvinga minimum of interference with the feeding of the thread.

Bobbin signals involving the invention in preferred forms will now bedescribed with reference to the accompanying drawing, and the featuresforming the invention will then be pointed out in the appended claims.

In the drawing:

Figure 1 is a schematic side elevation of a sewing machine equipped withthe bobbin signal of the invention;

Figure 2 is an enlarged elevational View taken on line 22 of Figure 1;

Figure 3 is a sectional View taken on line 3-3 of Figure 2;

Figure 4 is an enlarged fragmentary view showing a part of Figure 3 withthe gate in a second position;

Figure 5 is a perspective view of the bobbin of Figure 3;

Figures 6, 7 and 8 are sectional views taken on lines 6-6, 7-7 and 88,respectively, of Figure 5;

Figure 9 is a perspective view of a modified form of the bobbin;

Figure 10 is a sectional view taken on line 10-10 of Figure 9; and

Figure 11 is a perspective view of the gate of the bobbin in Figure 9.

In Figure 1, there is shown a sewing machine 1 of otherwise standard orknown type, to which has been added a signal light 2, and in which thebobbin and bobbin carrier assembly, indicated generally at 3, have beenmodified as best shown in Figures 2 and 3 of the drawing. The machine inthis case is of the usual lock stitch type, in which an upper thread isfed to a needle 4 and a lower thread is supplied from a bobbin.

The showing in Figures 2, 3 and 4 is generally schematic except as tothe bobbin. The sewing hook 11 is carried on the usual drive shaft 10and has the usual cutout positioned ahead of the point 12 of the hook inthe direction of rotation (clockwise in Figure 2).

A brush 14 mounted on and insulated from the hook 11 serves to makecontact with the bobbin when nearing exhaustion, and a second brush 14connected to brush 14 cooperates with a stationary contact 15 forclosing a circuit to the light L. The signal light L may be suppliedwith power in any convenient way, as by means of a transformer T andwill light when the circuit is completed from the brush 14 to the groundor machine frame in a manner disclosed below. The brush 14 is mounted toextend chordwise of the hook and diametrically 0pposite the edge 13 ofthe cutout, so as to prevent snagging of the thread as it leaves thebobbin.

Bobbin case carrier 16 fits in the sewing hook 11 and carries the bobbin20. Fixed to and insulated from the carrier 16 is an annular contactring 17. The insulating material 18 may conveniently be a liquid rubbercompound which will fully insulate and is easily applied, but anysatisfactory insulation may be used. The carrier 16 and bobbin case 19are otherwise of conventional construction.

As in Figures 5 to 8, one flange of the bobbin 20 has a cutout 21,extending partway into or along the bobbin barrel, and the upper end ofwhich is recessed or beveled as indicated at 22. Disposed on either sideof the cutout 21 are aligned inner grooves 23 and outer grooves 24spaced from one another by slots 25. These grooves receive the trunnionarms 29 of a gate or swinging contact 28. As can be seen in Figure 4,the upper or radially outward end of the gate 28 is held in the cutout21 against the recessed ledge 22 when the thread on the bobbin 20 bearsagainst the radially inward portion of the gate. The gate or contact 28is spaced from the contact ring 17 by a boss or raised face 27 on thebobbin 20. When the thread nears exhaustion, as indicated in Figure 3,the gate 28 may swing on the arms 29 and engages the contact ring 17 tocomplete the circuit, lighting bulb L and indicating to the machineoperator the lack of thread on the bobbin.

The gate 23 is preferably formed by bending a piece of spring wire toform upper and lower arms and trunnion extensions between them. Thetrunnion arms 29 are bent slightly as is shown in Figure 8, to give themsuiiicient spring force when the arms are inserted into their respectiveslots to swing the upper end or arm of contact gate 28 into contact withthe ring 17 when its lower end or arm is freed by the thread.

In Figures 9 through 11, there is shown a modified form of a bobbin 30having a similar set of grooves and slots. The grooves 23 and 24 and theslots 25 are positioned nearer the center of the bobbin. The bobbin 30also has a cutout 31 in its other flange, this cutout being alignedaxially with the cutout 21. A modified gate or contact 32 is housed inthe slots 21 and 31 and has its lower portion bent approximately fromits upper or contact portion 33, forming a bell crank having a contactarm 33 and operating arm 34. When the thread (not shown) is wound on thebobbin 30, the arm 34 is held to the barrel of the bobbin and thecontact or upper arm 33 is held back against the beveled edge 22 of theslot 21. The gate 32 is pivoted on the axis of the gate trunnion arms 35and 36, when inserted in the bobbin. The axis of arm 36 is displacedslightly from the axis of arm 35 as shown in Figure 11. The alignment ofthese arms when inserted in the bobbin stresses the gate 32, forcing itto swing into contact with the ring 17 when released by the thread.

What is claimed is:

1. A sewing machine bobbin comprising a barrel and flanges, a contactelement for signalling approaching exhaustion of thread on the bobbinand comprising a spring wire bent to form radially inward and outwardarms and trunnions extending to each side thereof, a flange of thebobbin being cut out and recessed to take the contact element andholding the same with its outward arm against a recessed outer surfaceof the bobbin flange and its inward arm against the thread woundthereon, the contact element being held in stressed position wherebyupon exhaustion of the thread to permit movement of the inward arm, theoutward arm is forced outwardly a sufficient distance to make contactwith a machine element.

2. A sewing machine bobbin comprising a barrel and flanges, a contactelement for signalling approaching exhaustion of thread on the bobbinand comprising a spring wire bent to form substantially coplanarradially inward and outward arms and trunnions extending to each sidethereof, a flange of the bobbin being cut out and recessed to take thecontact element and holding the same with its outward arm against arecessed outer surface of the bobbin flange and its inward arm againstthe thread wound thereon, the contact element being held in stressedposition whereby upon exhaustion of the thread to permit axially inwardmovement of the inward arm, the outward arm is forced outwardly asuflicient distance to make contact with a machine element.

3. A sewing machine bobbin comprising a barrel and flanges, a contactelement for signalling approaching exhaustion of thread on the bobbinand comprising a spring wire bent to form radially inward and outwardbell crank arms and trunnions extending to each side thereof, a flangeof the bobbin being cut out and recessed to take the contact element andholding the same with its outward arm against a recessed outer surfaceof the bobbin flange and its inward arm extending along the bobbinbarrel against the thread wound thereon, the contact element being heldin stressed position whereby upon exhaustion of the thread to permitmovement of the inward arm, the outward arm is forced outwardly asufiicient distance to make contact with a machine element.

4. A sewing machine bobbin comprising a barrel and flanges, a contactelement for signalling approaching exhaustion of thread on the bobbinand comprising inward and outward arms and trunnions extending to eachside thereof, a flange of the bobbin being cut out and recessed to takethe contact element and holding the same with its outward arm against arecessed outer surface of the bobbin flange and its inward arm againstthe thread wound thereon, the contact element being held in stressedposition whereby upon exhaustion of the thread to permit movement of theinward arm, the outward arm is forced outwardly a sufficient distance tomake contact with a machine element.

5. A sewing machine bobbin according to claim 4, in which the outer armand trunnions are held between the planes of the faces of the saidflange.

6. A sewing machine bobbin having a generally radial aperture on one ofits flanges and extending partway along its barrel, the flange beingrecessed on its outer surface at the radially outward end of theaperture to form a ledge, a contact signal element within the aperture,the radially outward end of the said element resting on the ledge andthe other end extending into alignment with the barrel surface forengagement by thread thereon to hold the said outward end against theledge, and means intermediate the said ends supporting the contactelement on the flange and yieldably urging it to rotate in a directionto bring its inner end inwardly along the barrel and its outer endoutwardly from the flanges.

7. A sewing machine bobbin signal comprising, in combination, a sewinghook, an aperture therein and a contact brush extending through theaperture to engage against a bobbin case carrier in the hook, thecontact brush extending chordwise from a point of attachment to permitpassage of a thread thereunder, a bobbin case carrier having a contactring on its inner and outer face, insulated from the carrier and engagedby the brush, and a bobbin having a contact element, means yieldinglyurging the contact element toward the said ring and means engaged bythread on the bobbin for holding the said element away from the saidcontact ring.

References Cited in the file of this patent UNITED STATES PATENTS2,227,303 Flaws Dec. 31, 1940 2,420,275 Winberg May 6, 1947 2,507,078Wright May 9, 1950

